Means for removing pit props



Aug. 4, 1953 w. LOEBBE 2,647,736

' MEANS FOR REMOVING PIT PROPS Filed April 6, 1950 Patented Aug. 4, 1953 2,647,736 MEANS FOR REMOVING PIT PROPS Wilhelm Loebbe, deceased, lateof many, by Armin Dieter Liibbe,

Oberaden, Germany Application April 6, 1950,

Oberaden, Geradministrator,

Serial No. 154,414

In Germany May 18, 1949 4 Claims.

This invention relates to a means for the sudden jerking away of pit props in mine workings, using an elastic traction element.

In order to knock away pit props in mine workings, it is known to employ resilient traction elements, for example, springs or rubber cables. With this arrangement, it has been the practice hitherto to connect the prop to be knocked away or extracted by the resilient traction element to the next row of props closer to the coal face. Immediately after it was released from the roof, the prop to be extracted was then suddenly jerked out of the range of the subsiding roof to a position beneath the supported roof nearer the coal face. It frequently happened however, that the prop or props to which the resilient extraction cable was connected under tension was still not loaded by an adequate roof pressure and thus still did not have the necessary stability. The result of this was that occasionally one or other of these props was demolished with the prop to be extracted.

According to the present invention, the resilient traction element for the sudden jerking away of a prop is tensioned between the latter and a prop spaced therefrom in the same row of props, but is deflected from an extended position by a support arranged nearer to the coal face. The support is advantageously formed by a compressional strut which is in the same row of props as the two props to which the extraction cable is attached and which is located between the said two props.

The extraction cable may consist of a wire cable or a chain, but it should not be extensible when a support by which the extraction cable is guided at anv angle is made to yield elastically. The support may, however, be rigid, or both the support and the extraction cable may be of resilient construction.

The invention will be described in further detail with reference to the drawing in which:

Fig. 1 shows a plan view of an embodiment of an apparatus in accordance with the invention and,

Fig. 2 shows a modification of the embodiment shown in Fig. 1 in which an elastic extraction cable is used.

The prop l and, subsequently, the other props ll, l2, l3 and M in the same row, which lie immediately in front of the breaking edge [5 of the roof, are to be extracted one after the other by the use of a resilient traction element by which, directly after the pressure of the roof is relieved, the prop I0 is jerked away towards the coal face out of the dangerous position. Hitherto, the elastic springing cable or several strands thereof have been stretched for this purpose up to the row of props Hi to 20, or even to a row of props which is even closer to the coal face. With this arrangement, however, it occasionally happened that one of the props l6-20 was demolished at the 56- 11 time, ince th row .01 P p quently was still not sufficiently loaded by the roof.

According to the present invention, however, in order to extract the prop l0, an extracting cable 22 is connected to the prop l3 which is in the same row of props it to I4 and it is deflected at an angle by a strut 23 which is supported against the prop II. The tensioning of the extracting cable 22 is brought about by an extractor jack 24 by reciprocating its actuating handle 24a.

In the example illustrated, the supporting strut 23 is of resilient construction and it comprises a spring casing 2311 with a spring 2312 which is compressed by the tension of the extracting cable 22.

Instead of providing the strut 23 with a resilient member, the extracting cable 22 itself could also be provided with such a member 22a as shown in Fig. 2 of the drawings.

The extraction of the prop I0 is effected by the extractor means 22 24 being first of all connected, in the manner shown in the drawing, to the props l0, II and I3. Thereupon, the cable is so strongly tensioned by actuating the jack 24 that the spring 23b of the strut 23 is compressed to a fraction of its original length. If now the lock of the prop I 0 is released, then immediately after the roof pressure is relieved, the prop is flung approximately in the direction 25 by the extraction cable 22 out of the range of the collapsing roof and underneath the part of the roof still supported by the remaining props H44 and l6-20.

What is claimed is:

1. Device for removing pit props in mine workings comprising an extraction cable with a prop attaching device positioned at each end, a strut with a prop attaching clamp at one end and attached at the other end to said extraction cable between its ends, a jack positioned for taking up said extraction cable, and an elastic element positioned to exert an elastic force against the taking up of said cable.

2. Device according to claim 1 in which said strut is a longitudinally compressible strut containing spring means positioned for exerting elastic force against longitudinal compression of said strut.

3. Device according to claim 1 in which said extraction cable is an elastic extraction cable.

4. Device according to claim 1 in which said extraction cable is non-elastic and said strut is longitudinally elastically compressible.

ARMIN DIETER LoBBE, Administrator of the estate of Wilhelm Loebbe,

deceased.

References Cited in the file of this patent UNITED STATES PATENTS 

